Burst shots, the same picture saved three times, near-identical photos from every angle — folders of images fill up with duplicates fast. Comparing them one by one gets slow as the count grows.
This guide shows you how to find similar and duplicate photos automatically with the free Image Similarity Checker. Your images are compared in your browser and never uploaded.
Sorting through photos for my blog, I kept wasting time picking between near-identical shots. I figured it would be faster if a tool pointed out the look-alike pairs first, so I built one.
How does it decide two images are similar?
The tool uses a technique called perceptual hashing. It shrinks each image to a tiny size, turns its pattern of light and dark into a short “fingerprint”, and then checks how closely the fingerprints match.
The advantage is that images that look the same are matched even if their file size or quality differs. The trade-off is that it doesn’t understand what’s in the picture — it can’t tell whether two photos show the same person, for example.
What this tool does
- Compares every pair among the images you choose
- Lists the pairs from most to least similar
- Marks likely duplicates as “Nearly identical” or “Very similar”
- Works entirely in your browser — your images are never uploaded
How to use it
Step 1. Open the tool
Open the Image Similarity Checker. There’s nothing to install and no sign-up.
Step 2. Choose the images to compare
Select two or more images at once. The comparison starts automatically as soon as they load.
Step 3. Review the similar pairs
Results are listed from most to least similar. Pairs labeled “Nearly identical” or “Very similar” are the likely duplicates. “Somewhat similar” usually just means the colors or composition are close, so treat those as a loose hint. Compare the thumbnails and decide which photo to keep.
Labeled pairs are the likely duplicates
Step 4. Clean up your folders
The tool never deletes anything. Use the results as a guide, then delete or move the photos you don’t need in your own folders.
Go by the labels rather than the percentage. Even completely unrelated photos can score 20–30% similarity.
When this comes in handy
- Sorting burst shots: pick the best one from a run of near-identical photos
- Finding accidental duplicates: catch the same image saved multiple times through downloads and copies
- Managing images for a blog or store: make sure the same product photo hasn’t been uploaded twice under different names
- Choosing photos for a project: narrow down a set of similar shots
FAQ
Does it find duplicates with different file names or dates?
Yes. It compares only how the images look, so different file names, dates or formats don’t matter. Equally, two files with the same name but different content are treated as different images.
Will it match the same image saved as JPEG and PNG?
Usually, yes. Images that were re-saved in another format or quality, or simply resized, typically show up as “Nearly identical” as long as they look the same.
How is this different from my phone’s duplicate finder?
Photo apps such as iPhone’s Duplicates album can find duplicates within your photo library. This tool is useful for images outside that library — files in folders on your computer, or photos split between your phone and your PC.
Things to watch out for
- Results are a guide: different photos with similar colors or composition can be marked as similar. Always check by eye before deleting
- Heavily cropped or rotated copies are harder to detect
- Large batches take longer: aim for a few dozen images at a time, and compare one folder at a time
- Need to spot tiny differences between two images? To see exactly which pixels differ between two same-sized images, use Screenshot Comparison
Summary
When similar photos pile up, let the tool find the look-alike pairs first, then choose — it makes sorting much faster. Your images are never uploaded, so it’s safe for personal photos too.
Try it on a folder of burst shots first.
